WMS:Eagleson Lag Time Equation: Difference between revisions

Revision as of 20:23, 26 February 2013

Eagleson’s method (1962) for computing lag time in completely storm-sewered watersheds is given as follows:

where:

$T_{LAG}$ = watershed lag time in hours.

$L$ = maximum flow length in miles.

$L_{ca}$ = length to the centroid in miles.

$S$ = weighted average slope of the maximum flow path in ft/mile.

The typical characteristics of watersheds for which the Eagleson method was applied include the following:

@@ Line 5: / Line 5: @@
 where:
-T<sub>LAG</sub> - watershed lag time in hours.
+<math>T_{LAG}</math> = watershed lag time in hours.
-L - maximum flow length in miles.
+<math>L</math> = maximum flow length in miles.
-L<sub>ca</sub> - length to the centroid in miles.
+<math>L_{ca}</math> = length to the centroid in miles.
-S - weighted average slope of the maximum flow path in ft/mile.
+<math>S</math> = weighted average slope of the maximum flow path in ft/mile.
@@ Line 17: / Line 17: @@
 *Areas from 0.22 to 7.5 square miles.
-*L from 1 to 7 miles.
+*<math>L</math> from 1 to 7 miles.
-*L<sub>ca</sub> from 0.3 to 3 miles.
+*<math>L_{ca}</math> from 0.3 to 3 miles.
-*S from 6 to 20 ft/mile.
+*<math>S</math> from 6 to 20 ft/mile.
 *Impervious cover from 33 to 83 percent.

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